You've been hired as a long term sub and you want to be a full-time teacher. Congratulations! We'd love to have you - and we know it is a bunch more money - and responsibility - than subbing. So let me help you!
There are school rules. You will be asked to enforce them. The students will not want you to enforce them because they are, after all, rules. Enforce them anyway.
When you don't enforce them - you make everyone's life harder. The students, the other teachers, the administrators, even the custodians. So, enforce the rules, even if you don't like them. Even if it makes the kids not like you a little.
Your basic responsibility is to keep the kids in the room. They want to go walking around the school. There will be conflicts. Keep them in the room. When you let them out into the hall, it makes it harder for everyone else in the hall to teach.
You will be given lessons to teach. Teach them. If you don't know how to teach it (which is not the same as knowing how to do it), ask. Do not say "it was too difficult for the students so I skipped it and now I am ready to test a week earlier" because you just messed up someone else's timeline.
Some courses have end of course tests. We teach to the test because the results matter. And by that I mean we have been given percentages of what is on the test and we parse the lessons accordingly. Sometimes we teach other things that are relevant but not necessarily on the test. We don't have time, when the test is 2 months away, to play movies every day, especially when the movies are pertinent to another department and absolutely will not be on an end of course test.
I have tried to tell you all of these things, but you assume I don't have a clue, that I am old and irrelevant. Ask yourself why certain things have happened lately and ask yourself if you are making yourself valuable or not to the organization you say you want to become a part of.
If another teacher steps in and repeatedly stops "traditions" you have set in place, they may be detrimental traditions. Or you can believe the other, older, actual teacher is a party-pooper. Your choice.